1. Field of the Invention
The present invention provides a method of manufacturing a painted golf ball with decreased static electricity on the surface of the golf ball prior to the painting to allow even painting to produce a ball without asperity thereon.
2. Description of the Background Art
Generally, a golf ball may be categorized in its structure as two types: a thread-wound ball and a solid ball. A thread-wound ball may be produced by extending rubber threads and winding them around a solid or liquid core and placing a cover around it. A solid ball may be formed by covering a hard-rubber core with one or more core outer layer(s) and a cover, and includes a one-piece ball, a two-piece ball or the like.
In any of these golf balls, the surface of the cover which forms the outermost layer is provided with a paint. The paint is generally formed of two layers: white and clear, and a clear paint layer provides the outermost surface. The paint layer is formed by a urethane resin paint.
There are a variety of property requirements for a paint, for example the toughness that enables a ball to resist large impact forces from the strike by a club face, and the flexibility that allows the ball to obey deformation caused by the impact. After the strike, when the ball falls onto the ground, it spins and is rubbed severely against turf, dirt, mud, gravel or the like, which causes decrease in shine due to wear, entrance of mud into the cuts, or adhesion of juice of the grass in the turf. In recent years, there is an increasing demand for a golf ball that retains its aesthetic appearance after use in terms of apparent whiteness and shine and, therefore, a ball ideally should exhibit good abrasion and cut resistance, be less easily contaminated and able to recover its original shine and whiteness after mud or the like is wiped off.
Conventionally, a paint for a golf ball is generally a urethane paint. For example, Japanese Patent Laying-Open No. 5-269221 uses a urethane clear paint including a hydroxy organic modified polysiloxane to allow maintaining the shock resistance of the coating and improve the ball's ability to slide for a long period of time. Specifically, the hydroxy organic modified polysiloxane used in the Japanese Patent Laying-Open No. 5-269221 is hydroxy polyester modified polysiloxane Byk-370 (from Byk Chemie Japan K.K.).
For cover materials, some techniques use a thermosetting polyurethane composition as described in U.S. Pat. No. 5,334,673, or a thermoplastic polyurethane elastomer as in U.S. Pat. Nos. 6,251,991 and 6,384,135.